Stormwater Infrastructure Asset Management Plan

Transcription

1 District of West Vancouver May 18, 2010

2 FINAL REPORT Prepared by: AECOM Canada Ltd Rosser Avenue, Floor 6, Burnaby, BC, Canada V5C 6S3 T F Project Number: ( ) Date: May 18, 2010

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4 May 18, 2010 Project Number: Phil Bates, P. Eng. Manager, Engineering Services District of West Vancouver th Street West Vancouver, V7VV 3T3 Dear Phil, Re: Final Stormwater Infrastructure Asset Management Plan Please find attached our final report for West Vancouver s Stormwater Infrastructure Asset Management Plan. We thank you for the opportunity to work with you on this interesting project. Sincerely, AECOM Canada Ltd. Nancy Hill, P.Eng. Project Manager Nancy.hill@aecom.com Encl: NH

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6 Version Log Version # Revised By Date Description 1 NH October 22, st complete draft 2 NH November 3, 2009 Revised Financial Scenario 3 NH February 4, 2010 Revised Plan based on West Vancouver s Dec 2009 comments and Jan 2010 revisions 4 NH February 10, 2010 Revised based on West Vancouver s February 9th comments 5 NH February 18, 2010 Revised based on West Vancouver s comments sent February 16 th. 6 NH February 24, 2010 Revised based on West Vancouver s comments sent February 24 th. 7 NH May 18, 2010 Corrected total replacement value. (aecom stormwater amp.docx)

7 Signature Page Report Prepared By: Report Reviewed By: Nancy Hill, P.Eng. David Main (aecom stormwater amp.docx)

8 Executive Summary Within its stormwater system, the District of West Vancouver owns and maintains 235 km of stormwater mains and associated appurtences (manholes/connections etc.), 522 culverts, 26 km of streams (within municipal right of ways), 19 detention basins, 136 grates, 1 oil-grit separator and 5 rain gauges. The replacement value of the system is estimated at $333 million. The results of this study provide the District of West Vancouver with a long range forecast (100 years) of the financial resources required to support the renewal of all of West Vancouver s stormwater assets. Figure ES.1 shows the stormwater system renewal requirements over the next 100 years in 2009 dollars. Current stormwater system renewal needs are estimated at $1 million per year but will increase to nearly $7 million per year by Currently, West Vancouver spends $400,000 per year to support the renewal of its stormwater system. Figure ES.1 also shows that on average the stormwater system will have replacement requirements of $3.7 million per year (which includes the backlog) over the next 100 years. Figure ES.1 Stormwater System Annual Replacement Requirements 100 Year Forecast $ 8 Culverts Estimated Annual Replacement Cost in million CAD $ 7 $ 6 $ 5 $ 4 $ 3 $ 2 $ 1 Other Creeks Storm Mains 100 year average Current Budget (aecom stormwater amp.docx) - i -

9 West Vancouver has approximately $2.2 million of backlog, which is shown in year 2009 in Figure ES.1. This backlog represents stormwater assets that are due for renewal, based on their age and/or condition, but have not yet been addressed. It is important to note that there were many data gaps with regard to the condition of West Vancouver s storm sewers and creeks. The financial projection in Figure ES.1 is based on assumptions where there was no data and on typical asset lifespan estimates. Changing these estimates will impact the capital renewal forecast as demonstrated in Figure ES.2. Figure ES.2 shows how the anticipated renewal requirements (cumulative) compare with the existing renewal budget, under three lifespan scenarios. The first scenario represents a best estimate of the lifespan of West Vancouver s stormwater assets (as depicted in ES.1). The best case scenario shows the stormwater system renewal requirements if the assets last longer than expected and the worst case scenario shows the stormwater system renewal requirements if the assets don t last as long as expected. The difference between the renewal requirements and the existing budget is known as the infrastructure gap. Under all three scenarios there is an anticipated infrastructure gap ranging from $287 to $409 million over the next 100 years. Under the best case scenario West Vancouver has 10 years to begin preparing for an infrastructure gap, but under the worst case scenario West Vancouver needs to begin addressing its infrastructure gap immediately. Figure ES.2 Projected Infrastructure Gap Three Scenarios $500 Cumulative Replacement Requirements in Million $ $450 $400 $350 $300 $250 $200 $150 $100 Worst Case Scenario Best Estimate Best Case Scenario Current Budget Infrastructure Gap $ million $50 $ (aecom stormwater amp.docx) - ii -

10 In general the anticipated infrastructure gap can be addressed by increasing the stormwater renewal budget and by optimizing the life cycle costs of assets. West Vancouver can reduce the lifecycle costs of its assets through an effective preventative maintenance program, by identifying the most cost effective renewal strategy for each asset, and by coordinating capital works wherever possible. In order to reduce costs in this manner, West Vancouver needs to collect and make use of more information about the condition and attributes of its stormwater mains and creeks within public right-of-ways. Therefore it is critical that the District implement its storm sewer condition assessment program and initiate a creek assessment program. This study has adhered to present day best practices for performing strategic level asset management. A needs-based approach has been taken to estimate annual resource requirements that give consideration to our current knowledge of asset life spans and current replacement costs. The relationships shown in Figure ES.3 illustrate the benefit of reducing lifecycle costs by 10% for each scenario, and provides a potential funding strategy that satisfies theoretical asset replacement requirements. This solution reflects one possible way that resources could be implemented throughout their lifecycle, not necessarily how those resources would be provided. Consideration has not been given to factors that might either accelerate renewal efforts (e.g. elevation of risk or criticality, resource levelling, opportunistic cost sharing), or decelerate renewal efforts (e.g. short term affordability). Additional factors, including future reserve policies, remain a subject for continued public debate. Ultimately, a budget-based approach to asset management will govern the extent to which West Vancouver will manage assets in a sustainable fashion over the short and long term. (aecom stormwater amp.docx) - iii -

11 Figure ES.3 Addressing the Infrastructure Gap $500 Cumulative Capital Replacement Requirements in Million $ $450 $400 $350 $300 $250 $200 $150 $100 Worst Case Scenario Worst Case -10% Best Estimate Best Estimate -10% Best Case Scenario Best Case -10% Current Budget Increased Budget $50 $ The results of this study illustrate the need for West Vancouver to fund its storm sewer condition assessment program, to prioritize assets for rehabilitation and to increase its stormwater capital renewal budget. Effective communication is critical to educate and engage stakeholders to assist in meeting the upcoming challenges associated with the management of the District s infrastructure. (aecom stormwater amp.docx) - iv -

12 Table of Contents Letter of Transmittal and Executive Summary 1. Introduction Asset Inventory What Do We Own?...2 page 2.1 Data Sources Asset Inventory Summary Replacement Costs: What is it worth? What is its? What Needs to be Done? When Do We Need to Do It? Risk Expected Service Life for Different Asset Types Sensitivity Analysis Bottom-up Asset Renewal Planning How Much Will It Cost? Long Range Forecast Funding Strategies: How Will We Pay for It? Current Funding Levels Future Strategies Infrastructure Funding Mechanisms Next Steps Adopting Asset Management Practices Recommendations Sustainable Funding Improving Asset Information and Optimizing Renewal Budgets Appendices A. Stormwater System Asset Inventory B. Storm Sewer Assessment Program C. Weibull Distribution Description D. List of Culverts and Grates in Poor (aecom stormwater amp.docx)

13 1. Introduction Figure 1.1 Seven Questions of Asset Management The District of West Vancouver commissioned this study to develop a long range forecast (100 years) of stormwater infrastructure renewal requirements to ensure the financial sustainability of its infrastructure in perpetuity. To help West Vancouver meet its objectives, AECOM developed this Asset Management Plan using the Seven Questions of Asset Management approach that is recommended by InfraGuide s Best Practice for Managing Infrastructure Assets. The results of each of the seven steps shown in Figure 1.1 are outlined in this report. This project leveraged work recently completed to satisfy PSAB reporting requirements and is being complemented by similar plans for West Vancouver s water and sanitary systems. The results of this plan can be used to assist in developing infrastructure renewal budgets, identifying replacement priorities, determining funding sources and communicating infrastructure needs to stakeholders. This plan covers all components within West Vancouver s stormwater system; namely 235 km of stormwater mains, 3,400 manholes, 522 culverts, 26 km of streams (within municipal right of ways), 19 detention basins, 136 grates, 1 oil-grit separator and 5 rain gauges. The renewal forecast for this study was completed using an MS-Excel based Capital Asset Planning (CAP) model. An electronic version of this model, with instructions for updating it, will be provided to West Vancouver. A print out of the stormwater system inventory from the model is provided in Appendix A. It is important to note that this model and the findings in this report provide a current snapshot of West Vancouver s stormwater infrastructure. If the system changes, for example, by the renewal of a storm main, then the model needs to be updated accordingly. All cost estimates have been prepared using current (2009) dollars in order to facilitate year to year comparisons and to avoid the uncertainty of projecting inflation and discount rates far into the future. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 1 -

14 2. Asset Inventory What Do We Own? 2.1 Data Sources Pipe inventories and creek lengths located within developed public right-of-ways were provided by the District of West Vancouver s GIS department in February The GIS data for storm mains is not as comprehensive as the water and sanitary sewer GIS data. With approximately 235 km of pipe, it is believed that the total length is captured. However most of the pipe material (65%) and some of the installation dates (19%) and pipe diameters (6%) are unknown (as shown in Figure 2.1). Figure 2.1 Storm Main Unknowns 70% 60% 50% Raw GIS data After Assumptions 40% 30% 20% 10% 0% Unknown Material Unknown Installation Date Unknown Diameter Where there were unknowns within the pipe inventory, assumptions were made as outlined in Table 2.1. In cases where the material type was unknown, the material type was assumed based on the year that the main was installed. If the installation year was also unknown, then the pipe material is labelled as unknown and given an average service life of 80 years. Where the pipe diameter and installation year were unknown, a weighted average of known diameters and installation years was applied to make assumptions for the unknown parameters. For example, if 30% of the L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 2 -

15 pipes with known diameters are 300 mm, then 30% of the pipes with unknown diameters were assigned a diameter of 300 mm. Using the weighted average on a significant portion of the inventory inevitably leads to a loss of accuracy. However, in the context of a high level life cycle analysis, the impact of using the weighted average, even on a large portion of the inventory, is not significant. Table 2.1 Assumptions Made for Unknown Storm Sewer Data If Then Assumed Diameter Material Installation Diameter Material Installation any unknown pre 1960 concrete 375 mm unknown post 1970 pvc >375 mm unknown post 1970 concrete unknown unknown 2001 weighted weighted average average 525 mm unknown 1995 concrete >375 mm unknown 1960s concrete < 450 mm unknown 1960s weighted average unknown unknown unknown weighted average Unknown (assumed average service life of 80 years ) weighted average Within the GIS database there were a variety of abbreviations given for the same material type. Table 2.2 outlines the various abbreviations within the GIS database and the material type assumed for this study. We recommend that the District adopt standard nomenclature for data such as pipe material to facilitate the collection and analysis of asset information. Table 2.2 Assumptions Made for Pipe Material Based on Abbreviations in GIS Pipe Material Unknown Asbestos Cement Cast Iron Vitrified Clay Wood Concrete Ductile iron High density polyethylene PVC Steel GIS Abbreviation 9999, blanks, NA, Inlet, RD AC CI VC, VITCLAY W, WD, WOOD conc, C, CP, RC, RCB, RCP DI HDPE, HDPP, SC BIGO, CPP, French Drain, Perf, PVC, PVC PERF CMP, ST, STEEL, CSP In 2006 West Vancouver compiled an inventory of all of its culverts and associated grates and headwalls. The information was compiled in a number of documents. A summary of the culvert inventory can be found in West Vancouver document DWV-# v1-RES.XLS. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 3 -

16 A detention basin inventory was compiled for PSAB in December The inventory which was used for this study can be found in West Vancouver document DWV-# v1-ASSET_PROJECT_- _STORM_SYSTEM.XLS. Natural creeks and water courses are considered part of the stormwater system. These creeks occupy both private and public lands. The District is responsible for the maintenance and rehabilitation of water courses that transit public lands. It was assumed that creeks within undeveloped areas are in their natural state and can remain as they are. However, creeks within developed areas will likely be impacted by adjacent development and will require rehabilitation work at some point in the next 100 years. It was determined from GIS that there are 26 km of creeks within developed areas and on public property. 2.2 Asset Inventory Summary West Vancouver s drainage system includes 235 km of stormwater mains and associated appurtances, 522 culverts, 26 km of streams, 19 detention basins, 136 grates, 1 oil-grit separator and 5 rain gauges. The 235 km of stormwater mains include all appurtances such as services, catch basins and storm manholes. As described in Section 2.1, asset attributes (such as material or installation date) are often unknown. In these cases, assumptions were made based on available information. A summary of the asset inventory used for this study, which includes any assumptions, is provided in the figures below. The pipe material is known for only 35% of the storm mains, which means assumptions had to be made about the majority of the inventory s material type. Figure 2.2 shows the breakdown of pipe material used for this study following the application of assumptions described in Section 2.1. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 4 -

17 Figure 2.2 VC 2, % Breakdown of Stom Main Materials (in metres) WOOD 1, % CI % AC % AC CI CON DI HDPE PVC STE UNK VC Asbestos Cement Cast Iron Concrete Ductile Iron Polyethylene (plastic) Polyvinyl chloride (plastic) Steel Unknown Vitrified Clay UNK 9, % CON 170, % STE 15, % PVC 29, % HDPE 2, % DI 3, % Following the application of pipe material assumptions, 80% of the mains are assumed to be made of concrete, 11% of PVC with the remaining 9% being made of a variety of pipe materials. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 5 -

18 Figure 2.3 Growth of Storm Sewer System by Pipe Type 40,000 Length (m) 35,000 30,000 25,000 20,000 15,000 WOOD VC UNK STE PVC HDPE DI CON CI AC 10,000 5,000 0 The growth of the storm sewer system by pipe type is shown in Figure 2.3. The oldest storm main in the system was installed in Some small sections of pipe were installed prior to 1963, but the majority of the system was installed after L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 6 -

19 Figure 2.4 shows that over half (57%) of West Vancouver s storm mains are 300 mm in diameter or less, approximately 25% are greater than 300 mm but less than or equal to 525 mm in diameter. The remaining 18% have a diameter greater than 525 mm. Figure 2.4 Length of Storm Mains by Diameter (in metres) mm 0.4 km 0.2% mm 0.1 km 0.1% mm 4.4 km 1.9% 300 mm km 57.3% mm 3.6 km 1.5% mm 2.3 km 1.0% mm 57.6 km 24.5% mm 7.0 km 3.0% mm 24.9 km 10.6% L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 7 -

20 3. Replacement Costs: What is it worth? The unit replacement cost for the storm mains include manholes and service connections. The estimated unit replacement costs were developed based on recent construction costs in the District of West Vancouver. The unit replacement costs (2009 dollars) for storm mains used for this analysis are provided in Table 3.1 below. Table 3.1 Unit Replacement Costs for Storm Mains Size (mm) $/m 300 $ $ $1, $1, $1, $1, $2, $3, $5,000 Most of West Vancouver s stormwater outfalls discharge directly on to the beach or rocky shoreline. As the outfalls are not submerged, the replacement costs do not include any underwater installation costs for renewing the outfalls. The unit replacement cost for the outfalls has been assumed to be the same as that for the storm mains. If future environmental or safety requirements significantly impact the design and/or construction of renewing outfalls, then the cost estimates will need to be adjusted accordingly. In most cases existing grates at the end of their service life will need to be replaced with new custom made and structurally sound grates. The unit replacement costs used for different types of grates are as follows: Screens - $5,000 Trash racks and grizzly racks - $30,000 The Manager of Sustainability, Environment & Healthy Communities for the District of West Vancouver confirmed that as culverts are replaced the District will look at installing baffles in the new culverts. In addition, new culverts should have grates and be designed for energy dissipation, as necessary. West Vancouver had already developed cost estimates for each of its culverts in 2008 for PSAB reporting, which were used for this study. The range of unit costs used ($50,000 - $160,000) were based on recent culvert replacement projects in West Vancouver. Factors considered in developing unit costs were the diameter of the culvert, the equipment required for installation (i.e. backhoe vs. excavator vs. crane) and the presence of a headwall. All culverts were assumed to have a length of 20 metres based on an average road width. The spreadsheet outlining the culvert replacement costs can be found in West Vancouver document DWV- # v1-ASSET_PROJECT_-_STORM_SYSTEM.XLS. Existing detention basins within West Vancouver use natural or recreational features. The only items that were included for future capital renewal works were inlet structures associated with these features. The L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 8 -

21 following list outlines the renewal cost used in this study for each of the detention basins. The irrigation reservoir within the golf course is operated by the Parks Division and has not been included within this study. Table 3.2 Renewal Cost for Stormwater Detention Basins Basin Renewal Cost 875 Fairmile $4,000 Whitby Road cul-de-sac $5,000 North of 3704 Southridge Place $4, /3712 Southridge Place $20, /3710 Southridge Place $20, /2790 Southridge Place $4, Westhill Drive $4, Westhill Drive $4, Westhill Drive $4,000 Woodburn at Westwood $10, Westhill Close $3, Westhill Place $4, Chelsea Close $4, Chippendale Road $3, /2531 Westhill Drive $4, Northwood $4, Westhill Wynd $10, Chelsea Close $4, Tyrol Place $5, Westhill Drive Westhill Wynd $4, Deer Ridge Drive $3,000 Total $205,000 Based on West Vancouver s experience with creeks within its jurisdiction, it has been assumed that all creeks within developed areas will require bank stabilization work at least once within the next hundred years. An estimate of $2,000 per metre for creek stabilization work was used based on an average unit cost of $1,000 per square metre for retaining structures, such as mechanically stabilized earth walls. Details regarding the condition of the creek banks on public property were not readily available for this study. Some information regarding the stream banks may be available within the Integrated Stormwater Management Plans (ISMPs) that West Vancouver has undertaken. Where there is no information regarding the stability of creeks on public property, we recommend that the District of West Vancouver undertake creek assessments to determine the rehabilitation required. The results of any creek assessments will help refine the funding forecasts developed as part of this study. Based on the assumptions documented in this report, West Vancouver s stormwater system has an estimated replacement value of $333 million (in 2009 dollars), a breakdown of which is shown in Table 3.3. Two-thirds of the value of the system is within its storm mains, 17% is within its culverts and 15% is within its L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx - 9 -

22 creek banks. The remaining 1% ( other ) consists of the detention basins, grates, oil-grit separator and rain gauges. Table 3.3 Replacement Value West Vancouver s Stormwater System Component Storm Mains Culverts Creek Banks Other Total Replacement Value $222.3 million $56.9 million $51.3 million $2.5 million $333 million In 2008, West Vancouver estimated that its stormwater system had a replacement cost of $272 million (reference DWV document -#332589). $272 million is lower than the estimate developed for this asset management plan ($333 million) as it doesn t consider any costs associated with rehabilitating creek banks. In 2006 UMA prepared a Multi-Year Storm Sewer Assessment Program for the District of West Vancouver. Within the summary report, the replacement value of the storm mains was estimated at $189 million. The 2006 estimate was a Class D estimate based on $2 per millimetre diameter per metre sewer. The estimate prepared for this plan is based on current construction costs in West Vancouver. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

23 4. What is its? West Vancouver recently completed an inventory of its culverts and associated grates. As part of the data collection, each culvert and grate was given a rudimentary condition grade of good, fair or poor. The majority of the culverts (88%) were rated as good, 10% as fair and 2% as poor. The majority of the grates (84%) were rated as good, 12% as fair and 4% as poor. A list of the culverts and grates noted to be in poor condition has been provided in Appendix D. Although these condition grades were based on a cursory visual inspection, they have been used for this study since West Vancouver does not have a more detailed condition assessment of these culverts and does not know the date that they were installed. We recommend that West Vancouver conduct a more thorough condition assessment of its culverts to develop a better estimate of future renewal needs. Recently West Vancouver staff discovered several storm mains that are deteriorating despite being only years old. The premature deterioration may be due to rocks entering the pipe system and scouring the inside of the pipe as they propel down the steep slopes at high velocities. To account for the fact that some mains are deteriorating prematurely, a Weibull probability distribution curve for predicting the timing of main replacement has been applied to this analysis. This will be discussed further in Section 6. In 2006 UMA developed a Multi-year Storm Sewer Assessment Program for West Vancouver, which can be found in Appendix B. Historically West Vancouver has done very little storm sewer condition assessment. We therefore recommend that West Vancouver implement the sewer condition assessment program as outlined in the 2006 report. Once West Vancouver determines the condition of its storm mains, it will be able to refine estimates of future funding requirements, prioritize mains for renewal and prolong the life of its storm mains through targeted rehabilitation work. The District of West Vancouver has typically conducted creek bank assessments only when an issue arises. West Vancouver has also completed Integrated Stormwater Management Plans for various watersheds that identify areas where stream bank erosion is a concern. However, West Vancouver does not have a comprehensive view of where and when stream bank rehabilitation works need to be conducted. It is recommended that West Vancouver extract available condition information from its ISMP s to plan the rehabilitation of its creek banks. Where there is no information on creeks that transit public lands in developed areas, West Vancouver should consider conducting creek bank assessments to better gauge the extent of stream rehabilitation works that may be required. It is important to note that this asset management plan addresses renewal based on asset condition. It does not address asset renewal in response to other factors such as capacity or environmental requirements. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

24 5. What Needs to be Done? To sustain the functionality of West Vancouver s stormwater system, numerous preventative and corrective maintenance activities must occur, and assets must be renewed as needed. In general, maintenance practices impact renewal requirements as effective preventative maintenance programs will help to extend the life of a given asset. Grouting, spot repairs, regular root cutting, video inspections and full replacement are some of the options that should be considered to determine the most cost effective strategy for operating and maintaining the storm sewer system. The optimal strategy will have to be reviewed on a case by case basis depending upon a variety of factors such as the age, location and structural integrity of the sewer. A good reference for the review of rehabilitation strategies for sewers is the Best Practice by the National Guide to Sustainable Municipal Infrastructure titled Selection of Technologies for Sewer Rehabilitation and Replacement. The InfraGuide Best Practice Reports can be found at West Vancouver should inspect its storm sewer system as recommended in the 2006 Multi-year Storm Sewer Assessment Program in order to identify optimal rehabilitation strategies. Other components of the stormwater system such as creeks, ditches, headwalls, grates and oil-grit separators also require regular inspection and maintenance to ensure their functionality and to optimize the life of each asset. As this study provides a high level view of asset renewal requirements, the maintenance and rehabilitation of specific assets such as the replacement of rip rap around culvert headwalls - has not been identified. Instead, all assets are assumed to require replacement at the end of their predicted service life, which provides a more conservative approach to budgeting than if rehabilitation strategies were also considered. In Section 7, the potential for extending the life of assets through a targeted rehabilitation program is discussed. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

25 6. When Do We Need to Do It? The CAP (Capital Asset Planning) model predicts the replacement year of an asset based on its age, the expected service life for the type of asset, its condition, and the consequences associated with its failure. In some cases replacement needs may also be based on externalities such as development but as these externalities are largely unknown at this time they have not been considered in this analysis. The model also assumes that the whole asset (i.e. culvert with headwall) is replaced at the same time. The model, which was developed for top-down asset renewal planning, can be used to estimate the remaining life of an asset but it is not an appropriate tool for determining short term capital programs. Identifying specific assets for replacement in the short term should be done in consultation with inspection results, maintenance records, capacity requirements and replacement programs of other utilities and roadways, and an understanding of the risk associated with a given asset failing. Short term capital planning should be done as part of a bottom-up asset renewal plan, as discussed in Section Risk The risk associated with a given asset failing can be defined as the probability of an asset failing (based on age, material and condition) multiplied by the consequences of it failing (defined as its criticality). Risk Exposure = (Consequences of Failure) X (Probability of Failure) The CAP model allows users to input a criticality rating to capture the level of damage or disruption that would be caused should an asset fail. As asset criticality has not yet been formally determined for West Vancouver s stormwater system, a criticality rating was not used for this analysis. This extra level of refinement could be done in a second more detailed renewal forecast. Additionally, once West Vancouver determines the criticality of different assets within its stormwater system it could use a risk based approach to determine the most cost-effective strategy for maintaining an asset based on the consequences of failure as depicted in Figure 6.1. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

26 Figure 6.1 Risk-based Approach to Asset Renewal Planning This risk-based approach is similar to that which was developed for West Vancouver s Storm Sewer Assessment Program by UMA in The objective of the Storm Sewer Assessment Program was to prioritize storm sewers for inspection and identify condition assessment requirements. As the objective of this study is to develop long term financial forecasts for renewing West Vancouver s sanitary system and not to prioritize the replacement of specific assets, the condition assessment risk model was not adopted for this study. However, we recommend that the risk model be used for prioritizing sewers for inspection and for a bottom-up renewal plan, as discussed in Section Expected Service Life for Different Asset Types A storm main s service life depends on many factors material, quality of installation, soil conditions, impact of rocks entering the storm system and disturbances by adjacent construction. Of these factors, West Vancouver, like most municipalities, only has information on the material of a portion of its storm mains. Fortunately, various industry sources exist that estimate a storm main s typical service life based on its material type. Table 6.1 summarises information on the estimated service life of storm mains that were collected from NASSCO (an industry organisation) and a survey from the National Water and Wastewater Benchmarking program. The table also outlines the service lives that were used for this study. The category Future is for any pipe that will be installed in the next 100 years. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

27 Table 6.1 Estimated Service Lives for Storm Mains by Material Type Estimated Material Service Life % of inventory Benchmarking Survey NASSCO AC % CI % 84 STE % 87 CON % DI % 87 HDPE % PVC % UNK % VC % WOOD % Future 100 As the majority of the existing pipes are concrete and PVC, the estimated service lives for these two materials will have the largest impact on the study findings. PVC pipe manufacturers claim that PVC will last 100 years, but since it has not been in the ground that long, a more conservative number of 85 years was used. This is consistent with what other cities across Canada are estimating for their PVC pipes as shown in the recent National Water and Wastewater Benchmarking Survey results. Although it was assumed that concrete will last on average 80 years, not all pipes will fail at exactly 80 years of life. To simulate the reality that not all pipes with an expected service life of 80 years will fail at exactly 80 years, the Weibull probability distribution was used to model a replacement envelope and predict pipe failure as the network ages. This means that a portion of the pipes will fail before its expected service life and a portion will last beyond their expected service life. More information about the Weibull Distribution can be found in Appendix C. The service lives used for assets other than storm mains are shown in Table 6.2. Table 6.2 Estimated Service Lives for Stormwater Assets Asset Type Estimated Service Life (years) Culverts 60 Oil-grit separator 50 Rain gauge 15 Screens 50 Detention Basins inlet structures 50 L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

28 As the installation dates of the existing culverts are unknown, the forecasted replacement year of the culverts was based on their condition. For this analysis, the forecasted replacement year was based on the following: All culverts in poor condition should be replaced within the next 5 years (i.e ); All culverts in fair condition should be replaced within the following 15 years (i.e ); and All culverts in good condition should be replaced within the remaining 40 years (i.e ). There is not sufficient information to determine when each creek on public lands will need to be rehabilitated. We therefore recommend that the District of West Vancouver complete a creek assessment program to better determine the current condition of the creeks and estimate the cost and timing of any required rehabilitation work. For the sake of this study, it was assumed that each creek within developed areas will require bank rehabilitation within the next 100 years. Therefore, the financial forecast has assumed that 1% of the creeks will require rehabilitation each year. As the District obtains additional information on the condition of its creeks, the assumptions made in this plan should be reviewed and refined as necessary. 6.3 Sensitivity Analysis The service life of concrete storm mains was estimated at 80 years based on industry standards and West Vancouver s limited CCTV data. Concrete pipe represents 52% of the value of West Vancouver s stormwater system. The cost of stabilising creek banks within West Vancouver had to be estimated in the absence of information on the condition of the existing creek banks. In order to test the sensitivity of the estimated service life of concrete pipe and the cost of rehabilitating creek banks worst and best case scenarios were developed in addition to the original best estimate. The range of values used for the three scenarios is presented in Table 6.3. Table 6.3 Range of Estimated Service Lives and Costs Used Asset Attribute Worst Case Best Estimate Best Case Creek bank stabilisation costs $5,000/metre $2,000/metre $500/metre Concrete pipe - average service life 60 years 80 years 100 years The impact of using a range of cost estimates and service lives can be seen in Section 7. If West Vancouver were to expand its CCTV program and creek assessment program, then it could better estimate how long its assets will last and refine the financial forecasts provided in this report. 6.4 Bottom-up Asset Renewal Planning This asset management plan represents a top-down approach to renewal planning, which is appropriate for strategic long-term planning and estimating future renewal budgets. A bottom-up asset renewal plan L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

29 identifies specific assets for replacement based on priority and is critical for optimising available renewal budgets. The bottom-up approach, which is used for short-term capital planning of projects, outlines asset renewal priorities based on asset condition and criticality. It is therefore important that West Vancouver determine the condition and criticality of its assets in order to develop a bottom-up stormwater asset renewal plan. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

30 7. How Much Will It Cost? This study estimates required capital renewal budgets over the long term, which facilitates the setting of capital budgets and associated revenue requirements. The District will still need to develop a prioritized capital renewal plan that identifies exactly which assets are to be replaced over the short term. 7.1 Long Range Forecast The main objective of this study was to provide West Vancouver with a long range forecast of future stormwater infrastructure renewal requirements. All costs presented in this report are in 2009 dollars, in order to provide a consistent view for year to year comparisons. If inflation were included, then it would be difficult to see if future cost increases were due to aging infrastructure or simply due to the selected inflation rate. Figure 7.1 shows the total annual capital replacement costs predicted by the CAP model for the next 100 years. The average annual cost over the next 100 years is $3.7 million (which includes the backlog). Replacement of storm mains represents the largest component of the total cost. Figure 7.1 Stormwater System Annual Replacement Requirements 100 Year Forecast $ 8 Culverts Estimated Annual Replacement Cost in million CAD $ 7 $ 6 $ 5 $ 4 $ 3 $ 2 $ 1 Other Creeks Storm Mains 100 year average Current Budget L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

31 The $2.2 million cost in 2009 represents the backlog of assets that are statistically due for replacement but have not yet been replaced. It would appear that the backlog predicted by the CAP model is accurate as West Vancouver operations staff have observed culverts and storm mains that are in poor condition, and in need of immediate repair. A large portion of the storm mains were installed in the 1960 s and 1970 s, probably in conjunction with the construction of the sanitary sewer system. This would explain why the stormwater replacement requirements peak to nearly $7 million around Figure 7.2 shows that the average annual estimated capital replacement cost over the next 25 years is $2 million (in 2009 dollars). The danger in taking a 25 year view is that West Vancouver won t be prepared for the signficant increase in renewal requirements in years Figure 7.2 Stormwater System Annual Replacement Requirements 25 Year Forecast Estimated Annual Replacement Cost in million CAD $ 4.50 $ 4.00 $ 3.50 $ 3.00 $ 2.50 $ 2.00 $ 1.50 $ 1.00 $.50 Other Culverts Creeks Storm Mains 25 year Annual Average Cost Current Budget As described in Section 6.4, a range of estimated service lives for concrete pipe and a range of estimated creek rehabilitation costs were used to determine the sensitivity of key assumptions. The total capital L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

32 renewal forecast using the original estimate of service lives as well as the worst and best case scenarios are presented in Figure 7.3 below. Figure 7.3 Total Annual Replacement Requirements Using a Range of Estimated Service Lives $9 Annual Replacement Requirements in $ Million $8 $7 $6 $5 $4 $3 $2 $1 Worst Case Scenario Best Estimate Best Case Scenario $ If the assets last longer than predicted (e.g. best case scenario) then the hump of renewal requirements is pushed further into the future and spread out over more years. If the assets don t last as long as predicted (e.g. worst case scenario) then West Vancouver will start to experience an immediate dramatic increase in renewal requirements. Conducting rehabilitation work, such as spot repairs, typically extends the life of an asset. However a sewer inspection program (CCTV) is required to identify opportunities for extending the life of sewer mains through rehabilitation. Therefore, we recommend that West Vancouver implement its Storm Sewer Assessment Program. The replacement costs in the 100 year forecasts above do not include CCTV or storm sewer repair costs. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

33 8. Funding Strategies: How Will We Pay for It? This study has estimated the total reinvestment requirements for West Vancouver s stormwater system over the next 100 years. It shows when the District can expect waves of high capital expenditures, thereby helping West Vancouver to better determine utility revenue needs and to optimise O&M practices to extend the life of existing assets. Now that West Vancouver has identified its stormwater capital reinvestment funding requirements, it can subtract any external contributions (i.e. from development or infrastructure grants) to determine required budget levels. 8.1 Current Funding Levels West Vancouver spends approximately $400,000 each year on the renewal of its stormwater infrastructure. Figure 8.1 shows how the anticipated renewal requirements compare with the existing renewal budget levels. The infrastructure gap measures the difference between the required capital renewal budget and the available capital renewal budget. Assuming that the stormwater capital renewal budget is only raised to keep up with inflation, the estimated infrastructure gap for the stormwater system by 2034 (i.e. in 25 years) is $44 million. Figure 8.1 Renewal Requirements vs. Existing Budget Levels 25 Year View $60,000,000 $50,000,000 $40,000,000 Cumulative Budget Cumulative Requirements $30,000,000 Infrastructure Gap by $44 million $20,000,000 $10,000,000 $ L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

34 As described in Section 6.3, a range of concrete pipe service lives and creek bank rehabilitation costs was used to determine the sensitivity of key assumptions. The infrastructure gap using the original estimate of service lives as well as the worst and best case scenarios are presented in Figure 8.2. Figure 8.2 shows that the current renewal budget is nearly sufficient for the best case scenario over the next 10 years. However, even in the best case scenario, the current renewal budget becomes significantly deficient after 20 years. Therefore it is recommended that West Vancouver take steps now, as discussed in Section 8.2, to address the pending infrastructure gap. Figure 8.2 Best and Worst Case Estimate of 100 Year Infrastructure Gap $500 Cumulative Replacement Requirements in Million $ $450 $400 $350 $300 $250 $200 $150 $100 Worst Case Scenario Best Estimate Best Case Scenario Current Budget Infrastructure Gap $ million $50 $ L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

35 8.2 Future Strategies The District needs to determine how it will address the forecasted infrastructure gap. The ultimate solution will likely come from a variety of sources: Extend the life of assets through a proactive inspection and rehabilitation program; Prioritize assets for replacement through a risk based bottom-up renewal plan (see Section 6); Reduce capital renewal costs through good asset management planning (see Section 9); Gradual but steady increase in capital renewal budgets; and Ensure that development driven improvements are partially or wholly funded by the development itself. Figure 8.3 shows the impact on the infrastructure gap if West Vancouver were able to reduce the lifecycle cost of its assets and increase its renewal budget. West Vancouver would meet the anticipated renewal requirements under the best estimate scenario if it reduced the lifecycle cost of its assets by 10% and increased its stormwater renewal budget according to the following schedule: : 20% annual increase (by 2015 the annual budget will be $2 million) : 0% annual increase (maintain $2 million budget per year) : $4.5 million budget per year : $5.8 million budget per year $2.3 million budget per year. The potential spending scenario illustrated in Figure 8.3 is theoretical and assumes that all assets will be replaced on a "just in time" basis. This information provides order of magnitude costs for the theoretical replacement; however, many factors will impact the actual rate of infrastructure renewal. Examples of some of these factors include assessments of risk or criticality, resource leveling, opportunistic cost sharing, short term affordability, and future reserve policies. These factors will be as important in the development of future capital financial planning as the physical replacement requirements identified by this theoretical replacement curve. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

36 Figure 8.3 Addressing the Infrastructure Gap $500 Cumulative Capital Replacement Requirements in Million $ $450 $400 $350 $300 $250 $200 $150 $100 Worst Case Scenario Worst Case -10% Best Estimate Best Estimate -10% Best Case Scenario Best Case -10% Current Budget Increased Budget $50 $ Effective communication is critical to educate and engage stakeholders to assist in meeting the upcoming challenges associated with the management of the District s infrastructure. Municipalities such as Edmonton and Hamilton have spent years quantifying their infrastructure renewal needs and communicating those needs to stakeholders. We recommend that West Vancouver use the information from this report and the National Water and Wastewater Benchmarking Initiative to inform senior management, City Council and the public on the following points: What assets does West Vancouver own? What are the assets worth? What is their condition? How much needs to be spent on infrastructure renewal? What is the relationship between renewal costs and maintenance costs? What is the level of service that West Vancouver residents receive? What is the relationship between infrastructure costs and levels of service? L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx

37 8.3 Infrastructure Funding Mechanisms Effective infrastructure renewal funding: Allocates costs to those benefiting from the service thus increasing equity in provision of services Supports accountability by clear allocation of funds Incorporates life cycle costs of infrastructure (i.e. depreciation, O&M and renewal) Provides reliable, predictable, dedicated funding to support multi-year infrastructure investment strategies Supports demand management efforts West Vancouver budgets approximately $400,000 of its general storm water funding each year to support the capital renewal of its storm water infrastructure. It is recommended that West Vancouver increase its funding for the capital renewal of its stormwater infrastructure in anticipation of the growing infrastructure gap. The District is also recommended to use a specifically designated reserve fund to collect renewal funding (similar to a capital reserve fund) that can be managed over a multi-year horizon. The results of this study are ideally suited for estimating the requirements of future reserves. It is important to note, however, that since the estimates in this study are based on 2009 replacement costs, they need to be revised on a periodic basis to reflect actual renewal costs in future years. Should West Vancouver want to investigate new funding mechanisms we recommend that the District refer to the National Guide to Sustainable Municipal Infrastructure s best practice titled Alternative Funding Mechanisms. The National Guide to Sustainable Municipal Infrastructure: Innovations and Best Practices is a compendium of technical best practices for addressing infrastructure issues. The best practice on alternative funding mechanisms describes eight methods for developing innovation funding sources to meet infrastructure needs, or to align costs with benefits to users. The eight alternative funding mechanisms described are Special Levies, Development Fees, Utility Models, Sponsorships, Innovative Transportation Revenues and Incentives, Government Service Partnerships, Funding Partnerships, and Strategic Funding Allocations. 8.4 Next Steps This study provides a long term view of infrastructure renewal needs. In order to determine infrastructure renewal priorities over the next 10 years, West Vancouver needs to conduct a bottom-up assessment of the stormwater system that considers asset condition, maintenance history, criticality, and coordination with roads and other utilities. This will allow West Vancouver to better quantify short term infrastructure renewal requirements and determine the actual impact on funding requirements. In order to conduct a bottom-up assessment, West Vancouver will need better information on the condition of its storm mains, culverts and creeks. To accomplish this, it is recommended that the District implement the program outlined in the 2006 report titled Developing a Multi-Year Storm Sewer Assessment Program (see Appendix B). As part of this program West Vancouver should also perform a more thorough review of the criticality of its stormwater system. Determining the criticality of different assets will allow West Vancouver to identify which assets can run to failure and which assets should be renewed before failure. L:\work\111000\111066\03-Report\AECOM Stormwater AMP.docx